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Use of Estimates, Assumptions and Judgements (Narrative) (Details)
 12 Months Ended
Dec. 31, 2019
$ / T
$ / oz
Gold Commodity Type [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity | $ / oz 1,380
Silver Commodity Type [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity | $ / oz 17.00
Lead Commodity [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity | $ / T 2,170.00
Zinc Commodity [member]  
Disclosure Of Detailed Information About Use Of Judgements And Estimates Explanatory [line items]  
Long term prices used for reserves and resource estimates related to commodity | $ / T 2,590